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Mainframers battle bugs in new virtualization

Early adopters offered strong support on the latest mainframe virtualization release z/VM 5.2. Customers especially liked the 64-bit upgrade, but some shops had an easier implementation than others.

SEATTLE -- Early adopters of IBM's latest mainframe virtualization software, z/VM 5.2, reported on the experience at the Share user group conference this week and lauded its new 64-bit capabilities. Project leaders from various companies said the increased performance on the release was worth the long hours of working out the bugs.

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"Get the new zVM if you want 64-bit storage relief," said Jim Vincent, systems engineering consultant at Columbus, Ohio-based Nationwide Insurance. "Z/VM will now scale better for large real-memory machines, large memory guests and systems. The final 64-bit code made a huge difference."

Previously, IBM offered partial 64-bit capabilities on z/VM, but operating systems and applications running on the virtual server couldn't access real storage above 2 GB. The latest version offers increased throughput for virtualized zSeries servers with large storage configurations, offering programs on z/VM to access real storage above 2 GB.

Martha McConaghy, systems, network and operations manager at Marist College in Poughkeepsie, N.Y., agreed, the biggest draw to z/VM 5.2 was the 64-bit capabilities. "You're not trying to shove everything below the 2 GB line anymore," McConaghy said.

McConaghy said Marist is running two mainframes, a z900 and a z990. Marist hosts the z990 through a joint project with IBM and the Open Source Development Lab (OSDL). It's a very lightly loaded system used for people who want to participate in the OSDL. The implementation of z/VM 5.2 on that system went off like clockwork.

Then it was on to upgrading the college's main production system, a z/900 that has four z/OS hosts and 500 plus Linux guests. It supports the college's library Web sites, e-mail and front-end Web-service with 3,000 users.

McConaghy said she had a warm fuzzy feeling about upgrading the z/900 after the easy upgrade on the z/990. Unfortunately, that turned out to be wrong. The production system ran for three hours before a CP command shut it down (HTT001 CP abend).

"IBM found the problem really quickly; there is a PTF for it. If you have this command on your system, it's not a high-priority fix," McConaghy said.

After applying the PTF, McConaghy tried to run z/VM 5.2 again, but after four hours she found out the virtual machines were hanging on logon messages and she could not reconnect to disconnected machines. "We got the message to logon and it just sat there. They would just hang. I couldn't get on anything to do a standalone dump."

McConaghy tried again the next week and it looked good for six hours, but the problems started again, and she noticed sending a message to a virtual machine would cause it to hang.

"Marist College I think is built on an Indian burial ground, so we find strange things other people don't," McConaghy joked. "It's something unique to what we're doing. No one else has had these problems."

McConaghy said she hasn't found the root of the problem yet but is narrowing down the possibilities. She thinks a program from CA Inc. called V/Seg may be related to the issue. "I've tried recreating the problem on my test systems and can't."

Despite the problems, early adopters said it was worth it.

"The conference calls can take a lot out of you. But it's definitely worth the work. We go in wanting to find problems because we want to find them before the general install," McConaghy said. "Overall, we were very satisfied with z/VM 5.2. While it was running, the speed improvements were impressive."

Vincent agreed, "You get to try all of the new stuff first and have key influence on the final product. We hit a couple potholes, but that's to be expected."

Let us know what you think about the story; e-mail: Matt Stansberry, Site Editor

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